Granting different rights to different citizens on the basis of race, gender, or sexual orientation is discrimination. Discrimination is wrong.
Any discrepancy between the legal rights of homosexual and heterosexual people amounts to discrimination. Legal discrimination of any kind has no place in society. Therefore, same-sex couples must be granted the same rights as heterosexual couples and be legally able to marry. Sexual orientation is a ‘protected characteristic’, and protected characteristics cannot be the basis of any discriminatory decision making. Not allowing same-sex marriage is an example of direct discrimination, which is described as treating someone with a protected characteristic less favourably because of that characteristic. Since marriage is the ultimate display of love and devotion, not allowing homosexual couples to get married is clearly treating them less favourably than heterosexual couples. Marriage equality is no different from any other form of equality. Equality before the law is a long recognised common law principle. Therefore, as long as a government claims that they believe in equality among human beings, they cannot vote against same-sex marriage or brand same-sex marriage as controversial . To do so would be discrimination on the basis of not treating homosexual couples equally to heterosexual couples on the basis of their sexual orientation.
If a gay couple can still access the same legal rights under a civil union then the law isn't discriminatory. They have still been granted the same legal rights, it would just be under a different name. At its core, marriage is a social institution designed to facilitate the care of children who are born of a sexual relationship between a man and a woman and to encourage both to be committed to the children and to each other. If the purpose of marriage is to facilitate childcare, and same-sex couples cannot have children together, then the purpose of marriage is defunct for same-sex couples. If marriage is an institution with a certain purpose rather than a human right, then it cannot be discriminatory to not allow same-sex marriage.
[P1] Discrimination is prejudicial treatment on the grounds of race, gender, religion or sexual orientation. [P2] Granting heterosexual couples more legal rights than gay couples is discriminatory. [P3] Marriage is considered a legal right. [P4] Therefore, denying gay marriage is discrimination.
Rejecting the premises
[Rejecting P2] Civil unions can provide the same legal rights to both heterosexual and homosexual couples.